Bow thruster



June 2, 1970 L G. THULIN BOW THRUSTER Filed 001;. 14, 1968 fassa!" FIG. 2 25 ff 2o IN VEN TOR.

02am/Jem@ 'United States Patent 3,515,088 BOW THRUSTER Lars Gustav Thulin, Goteborg, Sweden, assignor to Aktiebolaget Gotaverken, Goteborg, Sweden, a corporation of Sweden Filed Oct. 14, 1968, Ser. No. 767,257 Claims priority, application Sweden, Oct. 31, 1967, 14,888/ 67 Int. Cl. B63h 25/46 U.S. Cl. 114-148 3 Claims ABSTRACT OF THE DISCLOSURE Bow thrusters for ships are easily damaged by iloating objects and furthermore increase the resistance to flow. The bow thruster is used for a short time during navigation in to or out of harbours, respectively, and is inactive during the voyage. In order to prevent damages during the voyage the tunnel structure of the bow thruster is pivotable in such a manner that it may be swung away from the openings in the side plating of the ship. A considerable reduction of the resistance to flow is obtained if the tunnel structure is provided with means to cover said openings, when the thruster is inactive. When the thruster is located in a bulb projecting from the shipS fore body very high steering eiciency is obtained.

BACKGROUND OF THE INVENTION Many ships are nowadays provided with a bow thruster in order to facilitate navigation in narrow passages, Such a bow thruster comprises a propeller located in a tunnel structure, which is arranged in the bow portion of the ship, perpendicularly to the longitudinal axis thereof. The tunnel structure and the propeller may easily be damaged by foreign objects, which are forced into the tunnel as the ship passes through the sea. The openings of the tunnel will of course also bring about an increase in the resistance to flow along the ships sides.

SUMMARY OF THE INVENTION An essential improvement of the protection of the pertaining parts and a reduction of the resistance to ow will be obtained if the tunnel structure is designed as a unit separate from fore body and extending from one side plating thereof to the other and is pivotably mounted about a horizontal axis in the fore body, the side plating thereof being provided with openings corresponding to that of the tunnel structure. The bow thruster will hereby obtain an advantageous location far forward in the hull, which will bring about high steering eiciency. The shape of a bulb is well suited to accommodate the pivotable tunnel structure and the arrangement may easily be devised in such a manner that the openings in the side plating will be covered when the bow thruster is brouhgt into an inactive position.

BRIEF DESCRIPTION OF THE DRAWING FIG. l shows a detail of the 'bow portion of a ship provided with a protruding bulb in which the bow thruster is arranged.

FIG."2 shows a cross section along line II-II in FIG. l.

ICC

DESCRIPTION OF THE PREFERRED EMBODIMENT The ship 10 is provided with a bulb 11 of known design projecting from the underwater body of the ship. The bulb has a part-spherical front end 12 `and an essentially cylindrical body portion 13, which merges into the ships hull. This is immediately aft of the bulb provided with a watertight transverse bulkhead 14. T wo openings 15 are provided in the side walls of the cylindrical portion 13 located diametrically opposite to each other. In the bulb proper a tunnel structure 16 enclosing a propeller 17 is located. The propeller is in a manner known per se provided with adjustable blades and is mounted in a housing 18 in which an electric driving motor is arranged. The tunnel structure is pivotably supported in the bulb and in the bulkhead 14, respectively, and swingable about a horizontal axis 19 by means of power means 22 in such a manner that it can be swung essentially When the tunnel structure is brought into in its horizontal position it will co-operate with the openings 15, Iand when it alternatively is brought to a vertical position it is isolated therefrom. Two cover plates 20 are tted to the tunnel and designed in such a manner that they, when the tunnel has lbeen swung to a vertical position will cover the openings 15.

The end portions of the tunnel structure are provided with sealing means 23, which by means of pressure iluid operated rams 24 may be forced against the inner sides of the walls of the bulb. In a similar manner parts 25 of the cover plates may be pushed outwards by means of rams 26.

The means necessary for turning the tunnel and for transferring propulsion power to the motor may pass through bulkhead 14 in connection t0 shaft 19. Instead of designing the propeller with adjustable blades the driving motor may be reversible. The inside of the bulb may be kept dry by means of a drain pipe 21. In order to lessen the risk of corrosion during longer journeys the bulb may be filled with fresh water.

With -a propeller having xed blades and made to rotate in one direction only the tunnel is designed to be swung in order that the issuing thrust jet shall obtain the desired direction. The force of the thrust jet may in all embodiments be regulated by `turning the tunnel somewhat from the horizontal plane in such a manner that its ends only partly correspond to the openings 15 in the sides of the bulb. It is also possible to locate two propellers at some distance from each other in the same housing. This may then be supported in the tunnel by the shaft about which the tunnel is swung.

The tunnel structure may be mounted somewhat aft of the bulb proper. The portion of the fore body where the bulb merges into the hull will show areas concentric with the pivot axis of the tunnel structure which have sufficient extent to permit the arrangement of the openings 15.

I claim:

1. In a low thruster arrangement for a ship comprising a transversely arranged tunnel structure located in the underwater body of the ship and containing at least one propeller the characterizing features of a tunnel structure separate from the ships side plattwo oppositely located openings, one in each side plating of the hull, and

means to mount said tunnel structure for pivotal movement about a horizontal longitudinal axis in the 4 fore body of the ship to bring it in to or out of able sealing means displaceable outwards from the pivot alignment with said openings. axis for engagement with the inside of the side plating. 2. A bow thruster arrangement as claimed in claim l, in which the tunnel structure is designed to be swung References Cited about the pivot airis sufficiently to baring it O ll 0f 9011' 5 German Printed Appl., P. JaStram, No. 1,136,907 tact with the opening in the side plating and is provided September 1962 with cover plates, which in the inactive position of the tunnel structure will cover said openings. ANDREW H. FARRELL, Primary Examiner 3. A bow thruster arrangement as claimed in claim i1, in which the tunnel structure is provided with adjust- 10 

